High levels of the enzymes participating in the mitochondrial branch of the folate cycle, serine hydroxymethyltransferase 2 (SHMT2), methylenetetrahydrofolate dehydrogenase 2 (MTHFD2), and monofunctional tetrahydrofolate synthase 1L (MTHFD1L), have been linked to rapid proliferation in the NCI-60 panel of cancer cell lines [60]. This evidence concerns the gene SHMT2 and cancer.